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highmem.c

/* highmem.c: arch-specific highmem stuff
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/highmem.h>
#include <linux/module.h>

void *kmap(struct page *page)
{
      might_sleep();
      if (!PageHighMem(page))
            return page_address(page);
      return kmap_high(page);
}

EXPORT_SYMBOL(kmap);

void kunmap(struct page *page)
{
      if (in_interrupt())
            BUG();
      if (!PageHighMem(page))
            return;
      kunmap_high(page);
}

EXPORT_SYMBOL(kunmap);

struct page *kmap_atomic_to_page(void *ptr)
{
      return virt_to_page(ptr);
}

void *__kmap_atomic(struct page *page)
{
      unsigned long paddr;
      int type;

      pagefault_disable();
      type = kmap_atomic_idx_push();
      paddr = page_to_phys(page);

      switch (type) {
      /*
       * The first 4 primary maps are reserved for architecture code
       */
      case 0:           return __kmap_atomic_primary(4, paddr, 6);
      case 1:           return __kmap_atomic_primary(5, paddr, 7);
      case 2:           return __kmap_atomic_primary(6, paddr, 8);
      case 3:           return __kmap_atomic_primary(7, paddr, 9);
      case 4:           return __kmap_atomic_primary(8, paddr, 10);

      case 5 ... 5 + NR_TLB_LINES - 1:
            return __kmap_atomic_secondary(type - 5, paddr);

      default:
            BUG();
            return NULL;
      }
}
EXPORT_SYMBOL(__kmap_atomic);

void __kunmap_atomic(void *kvaddr)
{
      int type = kmap_atomic_idx();
      switch (type) {
      case 0:           __kunmap_atomic_primary(4, 6);      break;
      case 1:           __kunmap_atomic_primary(5, 7);      break;
      case 2:           __kunmap_atomic_primary(6, 8);      break;
      case 3:           __kunmap_atomic_primary(7, 9);      break;
      case 4:           __kunmap_atomic_primary(8, 10);     break;

      case 5 ... 5 + NR_TLB_LINES - 1:
            __kunmap_atomic_secondary(type - 5, kvaddr);
            break;

      default:
            BUG();
      }
      kmap_atomic_idx_pop();
      pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

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